Patent Application
20070245877
The present invention relates to an improvement in band saw apparatus and, particularly, a simplification of the apparatus including replacement of the conventional, upper idler wheel with a low friction guide surface. This arrangement will enhance the control of the tension in the band saw as well as reduce the expense in constructing and operating such machinery.
In the lumber industry, a number of apparatus has been employed to cut timber into usable pieces for subsequent operations or usage. Frequently, a wood cant must be cut into fairly thin but elongated pieces and typically band saws are used to accomplish this operation. In conventional band saws, such as represented by U.S. Pat. No. 4,061,066, issued Dec. 6, 1977, U.S. Pat. No. 6,745,644 issued Jun. 8, 2004, U.S. Pat. No. 5,1557,989 issued Sep. 24, 1996 and U.S. Pat. No. 5,819,613 issued Oct. 13, 1998, an endless band saw is looped around an idler pulley wheel and a drive wheel which is motor driven which is operated at high speed to rotate the drive wheel and, hence, the band saw over the pulley wheel while cants or wooden pieces are transported by a conveyor or manually against the cutting teeth of the band saw. Tension on the band saw is maintained by adjusting the distance between the central axis of rotation of the pulley and the drive wheel. The maintenance of the proper tension in the band saw loop is critical to efficient cutting operation and the avoidance of damage to the band saw loop. In particular, an improper low tension will result in wastage of the wood product since vibration of the loop will increase the size of the kerfs or cut made in the wood and can lead to breakage of the band itself.
In the present invention, the rotatable idler pulley is eliminated and replaced by a low friction curved surface that has one or more tracks for individual band saw loops. The drive wheel which is typically but not always located vertically below the surface provided by the present invention may be formed with a corresponding number of tracks to enhance guidance of the band saw or saws. In addition, the drive wheel may be provided with sprocket teeth to cooperate with sprocket openings formed along one edge of the band saw opposite the edge on which the cutting teeth are formed. Further, the track or each track of the curved surface is formed with a number of lubricating openings connected to a source of lubricant under pressure or continuous grooves which will also be supplied with a lubricant under pressure. Air under pressure may also be provided with the lubricant so that the band saw moving over the curved surface will encounter as little frictional resistance as possible.
One advantage of the arrangement of the present invention is the simplification of a band saw apparatus since the curved guide surface will require substantially less maintenance then the idler pulley currently in use. Also, typically the idler pulleys presently in use are relatively heavy as compared with the guide surface used in the present invention. The weight saving may significantly extend the life of the drive motor for the drive pulley. Additionally, the use of a fixed guide surface will allow the introduction of closely adjacent, multiple loop tracks which will be spaced apart at the cutting site by virtue of the different radii of each of the tracks as will become apparent from the following description. Further, the use of the stationary guide surface will reduce vibrations in the band saw during use and thereby result in a reduced kerf size and will allow thinner cutting to be accomplished.
The foregoing and other advantages will become apparent as consideration is given to the following detailed description taken in conjunction with the accompanying drawings, in which:
Referring to the drawings wherein like numerals designate corresponding parts throughout the several views, there is shown schematically in
As shown in the enlarged sectional view of
An alternative structure is illustrated in the top plan view of
With reference to a
Referring to
In
Slide 82 has an elongated arm 104 which has an upper slide surface 106 which is provided with a plurality of openings such as indicated at 108. The openings 108 are spaced across the surface 106 to underlie the band saw 112. The base member 102 is provided with a lubricant feed passage 110 which is supplied with a lubricant which may be mixed with air under pressure from a pump (not shown). The band saw 112 has its cutting edge extending beyond the end of arm 104 as shown.
A mechanism for spacing the slides 82-100 may include a set of drive screws such as indicated at 118 each of which is connected to a gear system 111 rotatably carried in each base member 102 to permit selective rotation of the gears and activation of corresponding drive screws to change the spacing between the arm 82-100. Separate electric motors (not shown) may be used to control selected ones of the gears of the system to effect independent movement of the slides toward or away from each other. This can be accomplished by control circuitry of a conventional type to allow selective actuation of selected gears 113 of the system.
Having described the invention, it will be apparent to those skilled in this art that various modifications may be made therein without departing from the spirit and scope of this invention as defined in the accompanying claims.
